Sirbasku D A, Moreno-Cuevas J E
The University of Texas-Houston Health Science Center, 77225-0036, USA.
In Vitro Cell Dev Biol Anim. 2000 Jul-Aug;36(7):428-46. doi: 10.1290/1071-2690(2000)036<0428:EMAINR>2.0.CO;2.
In an accompanying report (Moreno-Cuevas, J. E.; Sirbasku, D. A., In Vitro Cell. Dev. Biol.; 2000), we demonstrated 80-fold estrogen mitogenic effects with MTW9/PL2 rat mammary tumor cells in cultures supplemented with charcoal-dextran-treated serum. All sera tested contained an estrogen reversible inhibitor(s). The purpose of this report is to extend those observations to additional sex steroid-responsive human and rodent cell lines. Every line tested showed a biphasic response to hormone-depleted serum. Concentrations of < or = 10% (v/v) promoted substantive growth. At higher concentrations, serum was progressively inhibitory. With estrogen receptor-positive (ER+) human breast cancer cells, rat pituitary tumor cells, and Syrian hamster kidney tumor cells, 50% (v/v) serum caused significant inhibition, which was reversed by very low physiologic concentrations of estrogens. This same pattern was observed with the steroid hormone-responsive LNCaP human prostatic carcinoma cells. Because steroid hormone mitogenic effects are now easily demonstrable using our new methods, the identification of positive results has nullified our original endocrine estromedin hypothesis. We also evaluated autocrine/paracrine growth factor models of estrogen-responsive growth. We asked if insulin-like growth factors I and II, insulin, transforming growth factor alpha, or epidermal growth factor substituted for the positive effects of estrogens. Growth factors did not reverse the serum-caused inhibition. We asked also if transforming growth factor beta (TGFP) substituted for the serum-borne inhibitor. TGFbeta did not substitute. Altogether, our results are most consistent with the concept of a unique serum-borne inhibitor as has been proposed in the estrocolyone model. However, the aspect of the estrocolyone model related to steroid hormone mechanism of action requires more evaluation. The effects of sex steroids at picomolar concentrations may reflect mediation via inhibitor "activated" intracellular signaling pathways.
在一篇随附报告中（莫雷诺 - 奎瓦斯，J. E.；西尔巴斯库，D. A.，《体外细胞与发育生物学》；2000年），我们证明在添加了经活性炭 - 葡聚糖处理血清的培养物中，MTW9/PL2大鼠乳腺肿瘤细胞对雌激素有80倍的促有丝分裂作用。所有测试的血清都含有一种雌激素可逆抑制剂。本报告的目的是将这些观察结果扩展到其他对性类固醇有反应的人类和啮齿动物细胞系。每个测试的细胞系对激素缺乏的血清都表现出双相反应。浓度≤10%（v/v）时促进实质生长。在更高浓度时，血清逐渐起抑制作用。对于雌激素受体阳性（ER +）的人类乳腺癌细胞、大鼠垂体肿瘤细胞和叙利亚仓鼠肾肿瘤细胞，50%（v/v）的血清会引起显著抑制，而极低生理浓度的雌激素可逆转这种抑制。在类固醇激素反应性的LNCaP人前列腺癌细胞中也观察到了相同模式。由于使用我们的新方法现在很容易证明类固醇激素的促有丝分裂作用，阳性结果的鉴定使我们原来的内分泌雌激素介质假说无效。我们还评估了雌激素反应性生长的自分泌/旁分泌生长因子模型。我们询问胰岛素样生长因子I和II、胰岛素、转化生长因子α或表皮生长因子是否能替代雌激素的积极作用。生长因子不能逆转血清引起的抑制。我们还询问转化生长因子β（TGFβ）是否能替代血清中的抑制剂。TGFβ不能替代。总之，我们的结果与雌酮模型中提出的独特血清源性抑制剂的概念最为一致。然而，雌酮模型中与类固醇激素作用机制相关的方面需要更多评估。皮摩尔浓度的性类固醇的作用可能反映了通过抑制剂“激活”的细胞内信号通路的介导作用。
